When glass plates for use as liquid crystal panels are transported in a stacked state, interleaf sheets have been hitherto used for protection thereof. While paper was used as such an interleaf sheet, polyethylene-based resin foam sheets have been employed in recent years. (Patent Document 1, for example).
Foam sheets that are used as the interleaf sheets are required not only to have a cushioning property for protecting glass plates to be packaged but also to be low in degree of sag, when cantilever-supported, so that excellent handling property is achieved when they are inserted between glass plates. When the glass plates are subjected to processing and fabrication works, it is necessary to remove, by vacuum suction, the foam sheets inserted between the glass plates. In this case, if the foam sheets show an excessively high degree of sag when cantilever-supported, the efficiency of the removal procedures such as by vacuum suction will be deteriorated because portions of the foam sheets protruded from the glass plates are apt to hang down and foam sheets become wrinkled.
Patent Document 1: JP-A-2007-262409
On the other hand, in recent years, as glass plates for use in liquid crystal panels become larger and thinner, thinner foam sheets for use as interleaf sheets for such glass plates are demanded. Thus, there is an increasing demand for a thin foam sheet that has sufficient cushioning property as an interleaf sheet and, yet, that does not greatly sag.
It is, therefore, an object of the present invention to provide a multi-layer foam sheet which is thinner and lighter in weight than those of conventional multi-layer foam sheets for use as interleaf sheets and which has sufficient cushioning property and a low degree of sag and is suited for use as an interleaf sheet for glass plates for substrates.